1. Field of the Invention
The present invention relates to a manufacturing device provided with a pasting structure for a sealing substrate which seals elements (typically, a semiconductor element, a light emitting element, a memory element, a sensor, or a photoelectric transducer, each formed from a thin film transistor (hereinafter referred to as a TFT)). More particularly, the present invention relates to a pasting device for a sealing substrate which seals a light emitting element on the occasion of manufacturing a light emitting device which has a layer containing an organic compound as a light emitting layer.
2. Description of the Related Art
Recently, researches on a light emitting device comprising an EL element as a self luminous light emitting element are revitalized. This kind of light emitting device is called an organic EL display or an organic light emitting diode. Such light emitting devices have characteristics such as high response speed which suitable for displaying moving images, low voltage drive, and low power consumption, so that the light emitting devices draw keen attention as new-generation displays for mobile phones, personal digital assistants (PDA), and the like.
An EL element includes a layer containing an organic compound wherein electro luminescence can be obtained by applying electric field thereto, an anode, and a cathode. The luminescence with an organic compound can be broadly classified into two types: one is emitted when the singlet excited state returns back to the ground state (fluorescent light) and another that is emitted when the triplet excited state returns back to the ground state (phosphorescent light). Either or both types of the luminescence can be used for a light emitting device manufactured by a film forming mechanism and a film formation method according to the present invention.
A light emitting device has no problem with the viewing angle because it is a self luminous type, different from a liquid crystal display device. Accordingly, a light emitting device is better suited for outdoor use than a liquid crystal device, and various usages are suggested.
An EL element has a structure wherein an EL layer is sandwiched between a pair of electrodes, and an EL layer generally has a laminated structure. A laminated structure of “a hole transporting layer/a light emitting layer/an electron transporting layer” can be given as a typical structure. This structure brings extremely high luminous efficiency, so that most of the light emitting devices developed nowadays employs this structure.
Further, structures having the following layers laminated in order over an anode are also applicable: a hole injecting layer/a hole transporting layer/a light emitting layer/an electron transporting layer, and a hole injecting layer/a hole transporting layer/a light emitting layer/an electron transporting layer/an electron injecting layer. Fluorescent pigments or the like may also be doped into the light emitting layer. Furthermore, these layers may be formed from either of low molecular weight materials or polymer materials.
Note that, in this specification, all the layers provided between a cathode and an anode are referred to as EL layers generically. Accordingly, the above layers: a hole injecting layer, a hole transporting layer, a light emitting layer, an electron transporting layer, and an electron injecting layers shall be all included in an EL layer.
Furthermore, in this specification, a light emitting element formed from a cathode, an EL layer, or an anode is referred to as an EL element. The EL element is formed by two systems: a system in which an EL layer is formed between two types of stripe electrodes arranged so as to cross at right angles to one another (simple matrix system); and another system in which an EL layer is formed between a pixel electrode and a counter electrode, which are arranged in matrix and connected to a TFT (active matrix system). However, when the pixel density is increased, an active matrix system wherein a switch is provided for each pixel (or a dot) is considered advantageous because it is available for low voltage drive.
Further, an EL material forming an EL layer deteriorates extremely easily, and is easily oxidized or absorbs moisture. Therefore, a light emitting element has a problem of a decline in luminance or short lifetime.
Accordingly, in prior art, a light emitting element is covered with an encapsulating can; the interior is filled with dry air; and a desiccant is further adhered thereto, thereby preventing oxygen or moisture from reaching to the light emitting element.